Nutritional management of children with insulin-dependent diabetes mellitus (IDDM) traditionally has emphasized the exclusion of sucrose (sucr) because of concern that sucr contributes to poorer blood glucose (gluc) control. Our preliminary study in children with IDDM suggest that sucr may be used in mixed meals without an adverse glycemic response when fasting blood gluc concentrations are higher than ideal. Recent data in adults suggest that dietary sucr might have more of a glycemic effect if studied in subjects with euglycemic fasting levels of gluc. Thus, it is important to evaluate the glycemic effect of sucr under euglycemic conditions, particularly since many children eat high sucr snacks (sucr sweetened beverages, chocolate bars) without other foods with starch, protein and fat that may buffer or modify the glycemic response. Definitive studies that evaluate the glycemic effects of sucr in children who have excellent glycemic control are unavailable. Moreover, the glycemic effect of high sucr-containing snacks given without other foods is not established. The objectives of these studies in 20 children (7-12 years) with well controlled IDDM are: Study 1: Compare glycemic effects of sucr-free (Suc-Free, 2% kcal as sucr) and sucr-containing (Suc-Con, 10% sucrose) meals/snacks when fasting gluc concentrations are between 100 and 150 mg/dl (10 children). Study 2: Compare glycemic effects of Suc-Free diets and Suc-Con diets that include high sucr snacks without other foods (10 additional children). In each study, children will be randomized in a crossover design to receive both diets and a constant insulin dose for 2 consecutive 2-day periods in the Clinical Research Center. Diets for both studies will be isocaloric (50% carbohydrate, 30% fat, 20% protein) with identical fructose, gluc and fiber in 3 meals and 3 snacks. In Study 1, sucr isocalorically replaces starch in mixed meals/snacks. In Study 2, sucr replaces starch in mixed meals; however, snacks will be high sucr foods eaten without other foods. For both studies, glycemic response of both diet periods will be compared with x fasting plasma gluc, total area under the gluc response curve (7:30 am to 9:30 pm) and 24-hr urinary gluc excretion. Also, for Study 2, the x baseline, 1/2 and 1 hr gluc, ? from baseline to 1/2 and 1 hr, and the area under the gluc response curve will be compared for the snacks of the 2 diet periods.